1564396449
详细说明: - 添加了V2版本的工作流页面和结果页面 - 更新了Serena记忆文件 - 添加了详细实施计划文档 - 优化了Vite配置 - 更新了项目文档CLAUDE.md - 构建了演示系统的dist版本 - 包含了exhibition-demo的完整依赖
77 lines
2.0 KiB
Markdown
77 lines
2.0 KiB
Markdown
# `dlv(obj, keypath)` [](https://npmjs.com/package/dlv) [](https://travis-ci.org/developit/dlv)
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> Safely get a dot-notated path within a nested object, with ability to return a default if the full key path does not exist or the value is undefined
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### Why?
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Smallest possible implementation: only **130 bytes.**
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You could write this yourself, but then you'd have to write [tests].
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Supports ES Modules, CommonJS and globals.
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### Installation
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`npm install --save dlv`
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### Usage
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`delve(object, keypath, [default])`
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```js
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import delve from 'dlv';
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let obj = {
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a: {
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b: {
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c: 1,
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d: undefined,
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e: null
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}
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}
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};
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//use string dot notation for keys
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delve(obj, 'a.b.c') === 1;
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//or use an array key
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delve(obj, ['a', 'b', 'c']) === 1;
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delve(obj, 'a.b') === obj.a.b;
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//returns undefined if the full key path does not exist and no default is specified
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delve(obj, 'a.b.f') === undefined;
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//optional third parameter for default if the full key in path is missing
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delve(obj, 'a.b.f', 'foo') === 'foo';
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//or if the key exists but the value is undefined
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delve(obj, 'a.b.d', 'foo') === 'foo';
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//Non-truthy defined values are still returned if they exist at the full keypath
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delve(obj, 'a.b.e', 'foo') === null;
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//undefined obj or key returns undefined, unless a default is supplied
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delve(undefined, 'a.b.c') === undefined;
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delve(undefined, 'a.b.c', 'foo') === 'foo';
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delve(obj, undefined, 'foo') === 'foo';
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```
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### Setter Counterparts
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- [dset](https://github.com/lukeed/dset) by [@lukeed](https://github.com/lukeed) is the spiritual "set" counterpart of `dlv` and very fast.
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- [bury](https://github.com/kalmbach/bury) by [@kalmbach](https://github.com/kalmbach) does the opposite of `dlv` and is implemented in a very similar manner.
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### License
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[MIT](https://oss.ninja/mit/developit/)
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[preact]: https://github.com/developit/preact
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[tests]: https://github.com/developit/dlv/blob/master/test.js
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